Heat removal is a prominent factor in a computer system and data center design. The number of high performance electronics components such as high performance processors packaged inside servers has steadily increased, thereby increasing the amount of heat generated and dissipated during the ordinary operation of the servers. The reliability of servers used within a data center decreases if the environment in which they operate is permitted to increase in temperature over time. Maintaining a proper thermal environment is critical for normal operations of these servers in data centers, as well as the server performance and lifetime. It requires more effective and efficient heat removal solutions especially in the cases of cooling these high performance servers.
Power intensive processors enable the solution of intensive computing such as deep learning. Electrical servers having those processors, i.e., high-power central processing units (CPUs) and/or general-purpose processing units (GPUs), have a very high power density per volumetric space, and hence, traditional simple air cooling is very challenging. Direct-to-chip liquid cooling provides a better cooling performance for those power-intensive processors, and saves energy consumption compared to an air-cooling only approach. Practically, not all the heat generated by the processors is removed through liquid cooling, and there is still some percentage of heat is removed by air cooling. Thus the entire environment is a hybrid liquid-air cooling system. In a hybrid liquid-air cooling system, a liquid flow rate is controlled via pump speed control in a coolant distribution unit (CDU), and an airflow rate is controlled via fan speed control on the back of an electronic rack. Conventional cooling systems have not been efficient enough to reduce energy consumption of the cooling systems.